The FRED series Total Credit Market Debt Owed by Domestic Nonfinancial Sectors - State and Local Governments is now known as State and Local Governments, Excluding Employee Retirement Funds; Credit Market Instruments; Liability.

As stated on the December 08, 2011 release:
The instrument tables on municipal securities and loans (tables F.211 and L.211) have been revised from 2004:Q1 forward to reflect a change in data sources. Data on debt outstanding and net issuance for state and local governments, nonprofit organizations, and nonfinancial corporate business
(industrial revenue bonds) are now based on data from Mergent, a private data vendor. The new data indicate that municipal securities and loans
outstanding in 2004:Q1 is $740 billion greater than previously estimated in the flow of funds accounts.
The estimate of household holdings of municipal securities and loans is revised up by about $840 billion, on average, from 2004 forward.